Not going to happen.
There are way to many game play issues involved and way to much work to be spent for virtually nothing. The only thing more than 2 factions will accomplish is less people to group with and a different tag.
It also hardly makes any sense lore wise. Forsaken going out of the horde would make some sense but any race allying with them won't, because if they want to raise everyone as undead, the rest are living you know. It would be both easier and much more convenient for the living races to destroy the undead and their "corruption".

What's up with the 3 factions nonsense anyway?

Oh, and about World of Starcraft, that won't happen anywhere in the next 3-4 years if ever. SC2 already has another expansion planned StarCraft II: Legacy of the Void.

If the forsaken became a third faction because sylvannas leaves/gets kicked from the horde.
Well of course the already forsaken in the horde become the type who stay in the horde and follow the warchiefs ways.

While sylvannas is doing her own thing, such as killing people to resurrect them as her own?
We can already say she's become her own type of lich king, I wouldn't be surprised if she does something outrageous at the end of MoP.

Whoa slow down buddy ...

Lady Sylvannas doesn't kill random living things to ress them as her soldiers...she ress's the dead or take over what was so called as scourge and gives them free will and by doing this they stick to her.

I always wished there was a Forsaken faction that we could join apart from Horde/Alliance stuff.

Cenarion Circle aligns with Alliance and Forsaken aligns with Horde for group content. Pandaren are still neutral.

I didn't forget them, I left them out intentionally and I explained why. Tauren are supposed to be bigger and more powerful, gnomes and pandaren are a joke, goblins are to be neutral, draenei are out of place. We don't need more races. The world already has a clusterfuck of cultures and styles, in which an individual race barely has a couple of lines of lore and two or three building models. Look at worgen, gnomes, draenei, pandaren. They barely got some attention at the start, now they are forgotten. Pandaren only belong to this expansion, they feel completely out of context outside Pandaria and you can be sure that their involvement in Azeroth ends with MoP.

Less quantity, more quality.

---------- Post added 2013-05-08 at 12:42 PM ----------

Originally Posted by Verdugo

And one wins over all of them because developers really like their space elves.

You mean Blood Ravens chapter which wins in canon? I thought Eldar were gayelves of Warhammer.

"A NAME IS A CLOAK OF LETTERS THROWN UPON A MAN. IT MEANS NOTHING." - Transcendent One, Planescape: Torment.

Everyone has already covered how it isn't going to happen so I'll skip to why conceptually it's a bad idea. The Forsaken fits Horde like a glove, and is an important part of what the Horde actually is. If the Forsaken were to leave the Horde, then there'd only be two fallen races with a fractured past fighting to redeem themselves and to carve themselves a place in a world that doesn't want them (Belves and Orcs). Goblins, Tauren, and Trolls factions are in the Horde because their leaders made a deal witth Thrall, who isn't even Warchief anymore (he wasn't even Warchief when he let the Goblins into the Horde, somehow). Pandaren shouldn't even be in the Horde.

If there was to be a third playable faction, impossible in WoW but hypothetically, or perhaps for WCIV or WoW2, it should be basically insane and evil. An old god faction comprised of Naga, murlocs, Qiraji, Faceless ones, and ogres. Then you work to portray the Alliance heroically, the Horde Anti-heroically, and the old god faction villainously. All three hate each other and are kill on sight. All three would have a common enemy in the Burning Legion.

1. They'll never split races from their factions, because that would make people unable in many cases to keep playing with their friends.

2. Making a third faction is no simple thing. First of all, they'd have to make FURTHER changes to make sure the Alliance and Horde both still have the same number of capital cities and races. Then, they'd have to make sure this new faction also has an equal stake compared to the Horde and Alliance. Third, they'd have to revamp the entire 1-90 experience because right now, the two faction system is baked into everything from questing hubs to battlegrounds. A third faction would mean they'd need content for that faction to quest in. They're just not going to do this.

The ONLY way we MIGHT see a three faction game is if Blizz releases another MMO in the future, such as World of Starcraft or WoW2. But WoW will never become a 3 faction game. It would require them to overhaul way too much.

Beside, 1 faction against the ENTIRE world (aka Horde and Alliance)?
Not bloody likely.

Beside, 1 faction against the ENTIRE world (aka Horde and Alliance)?
Not bloody likely.

Who says they would be against united Horde and Alliance. Those two factions are full of idiots, just do some slaughter, plant evidence against each other and you have disorganized skirmishes in no time.

Where do you guys come up with these bizarre nonsensical ideals? They are never going to split an existing race from an existing faction to make another, players enjoy playing what they are with the people that they play with and blizzard would never make you split from your friends.
If blizzard did this they would have an explosion from at least half the player base. I’m not a big fan of Panderan in the Horde but I know that now that the pool is in the pee you are never going to seperate them again.

Now that does not mean Sylvannus can’t end up splitting from the forsaken, not all Forsaken are beholden to her and many forsaken are loyal to the horde and their friends within the horde. Upon creation those undead that retain free will are given the option of serving Sylvannus and the Forsaken and they can choose to not serve at all, the very core of the foresaken is that they have the right of choice, they are not mindless automaton scourge that are forced to serve a lich King.

Blizzard also wont make a 3rd faction because you would have to go through 90+ levels worth of content and create towns and quest hubs so that the new faction can level up to max. The level of redesign required would dwarf the effort made in Cata to redisgn just the 1-60 content which Blizzard has stated may of been a mistake since their efforst were not placed in 85 content.

I didn't forget them, I left them out intentionally and I explained why. Tauren are supposed to be bigger and more powerful, gnomes and pandaren are a joke, goblins are to be neutral, draenei are out of place. We don't need more races. The world already has a clusterfuck of cultures and styles, in which an individual race barely has a couple of lines of lore and two or three building models. Look at worgen, gnomes, draenei, pandaren. They barely got some attention at the start, now they are forgotten. Pandaren only belong to this expansion, they feel completely out of context outside Pandaria and you can be sure that their involvement in Azeroth ends with MoP.

Less quantity, more quality.

---------- Post added 2013-05-08 at 12:42 PM ----------

You mean Blood Ravens chapter which wins in canon? I thought Eldar were gayelves of Warhammer.

Blood ravens won only due tactical genius of indrick boreale. That and his motivational speeches.
BATTEL BRAVAS !!!!
And don't forget that gaybriel angelos also have some time to shine.

Well Forsaken can be a 3th faction in fact they are you still start as neutral to other horde major city`s
Its just about changing some lore and quests and voala we will got 3th faction who do her own things and players are just some renegads/rebels who join to the Horde forces at some point of their leveling

Where do you guys come up with these bizarre nonsensical ideals? They are never going to split an existing race from an existing faction to make another, players enjoy playing what they are with the people that they play with and blizzard would never make you split from your friends.
If blizzard did this they would have an explosion from at least half the player base. I’m not a big fan of Panderan in the Horde but I know that now that the pool is in the pee you are never going to seperate them again.

Now that does not mean Sylvannus can’t end up splitting from the forsaken, not all Forsaken are beholden to her and many forsaken are loyal to the horde and their friends within the horde. Upon creation those undead that retain free will are given the option of serving Sylvannus and the Forsaken and they can choose to not serve at all, the very core of the foresaken is that they have the right of choice, they are not mindless automaton scourge that are forced to serve a lich King.

Blizzard also wont make a 3rd faction because you would have to go through 90+ levels worth of content and create towns and quest hubs so that the new faction can level up to max. The level of redesign required would dwarf the effort made in Cata to redisgn just the 1-60 content which Blizzard has stated may of been a mistake since their efforst were not placed in 85 content.

Pretty sure you didn't read my entire post.

"Behold those who have power, and who are not afraid to wield it. Behold... the warlocks!"

What might happen is Sylvanas and a group of (NPC) loyalists leave the Horde and become either a neutral faction, or an enemy faction (more likely), Forsaken getting a new leader, and Sylvanas eventually becoming a raid boss.